hce 0.6.3

• Added a NEWS.md file to track changes to the package.
• The hex sticker of the package has been created and is included in all vignettes.
• HCE1 - HCE4 datasest are upadted to follow the standard structure.
• A new argument dec is added to simHCE() for decimal places used for rounding the continuous outcome in the simulated dataset. Additionally, the default value for the standard deviation of the continuous variable in the placebo group CSD_P is changed to be equal to that of the active group CSD_A instead of being equal to 1.
• A new function simHCE() which simulates adhce objects, that is, an hce object with its source datasets. Works similar to simHCE() which provides only an hce object.
• A new function simORD() which simulates ordinal endpoint by categorizing beta distributions.